/Engine/Source/Runtime/OpenGLDrv/Public/OpenGLDrv.h
This method is queued with an RHIThread, otherwise it will flush after it is queued; without an RHI thread there is no benefit to queuing this frame advance commands.
virtual void RHIEndDrawingViewport ( [FRHIViewport](API\Runtime\RHI\FRHIViewport) * Viewport, bool bPresent, bool bLockToVsync )